Camera LUT Options
Working with Camera Options for Look LUT generation.
The 'Camera' option within the Colour Space options enables the use of Camera data, as provided by the supported camera manufacturers, to generate Conversion and Look LUTs for any Destination colour space, camera to camera conversion LUTs, and more. The Camera Options are available with the LightSpace LUTs+, LightSpace PRO and LightSpace XPT licenses.
Presently supported camera manufacturers are: Sony, Arri, Canon, RED, Panasonic, Blackmagic, and DJI, plus a generic Rec709 camera, with other added as and when different manufacturers provide access to the camera's technical data.
Camera Technical & Look LUTs
The Camera Settings options enable the generation, previewing, and analysis of Look and Technical Conversion LUTs for a range of digital cinematography cameras, specifically those that shoot and capture Log and Wide Colour Gamut.
The LUTs generated within LightSpace CMS are 'technically' correct, based on the camera data provided by various manufacturers, which means they will often be 'different' from the Look LUTs provided by the same manufacturers, as the manufacturer LUTs often contain undocumented LUT manipulations to try to 'improve' the look of the final image.
This undocumented manipulation of manufacturer LUTs is not 'wrong', nor a cheat, but does mean it can be difficult to assess the true image capture capabilities of any given camera without using technically correct LUTs, as can be generated via the LightSpace CMS Camera Settings option.
Generating camera to camera technical conversion LUTs can be particularly telling over the true underlying capabilities of different cameras.
The LightSpace CMS Camera options uses colour and gamma data provided by the various camera manufacturers, with various options available depending on the camera format and value manipulations specified by the manufacturer.
When the Camera option is first selected tabs for the different camera formats, as well as a default Rec709 camera, are available. Each tab provides various options for the different camera formats, as specified by the different camera manufacturers.
Tone Mapping provides a Viewing option and 3 pre-sets for tone mapping - Low, Medium, & High'. Used in combination with the Peak Luminance Mapping and Push/Pull Exp. options this will provide aesthetically pleasing highlight and low-light roll-off, depending on associated Camera Options settings.
All Tone Mapping options are based on generating 'Viewing LUTs', negating the inbuilt camera transfer profile linear portion near black. See below for further details.
Push/Pull Exp. (Stops) enables alteration of the expected exposure of the underlying footage, in Stops. Can be used in isolation, or in combination with Tone Mapping and Peak Luminance Mapping.
Peak Luminance Mapping sets the clip point for the generated LUT, clipping all over-range data.
This control functions as an exposure control, so 100% would be the nominal value for correctly exposed footage displayed on a standard monitor, with any value used for creative Look LUT generation. Can be used in conjunction with Tone Mapping and Push/Pull Exp.
Set Black sets the expected black point (level) for the camera output, which is used to correctly calculate the Transfer Function during generation of the LUT. Note: this is not setting the black point of the generated LUT.
Set White sets the expected white point (level) for the camera output, which is used to correctly calculate the Transfer Function during generation of the LUT. Note: this is not setting the white point of the generated LUT.
Note: if a LUT needs to perform rescaling, say from Video Range to Data, the LUT Manipulation Tools should be used.
Transfer Function selects the desired transfer curve from a drop-down list defined by the camera manufacturer. Different camera formats have different options. The selected Transfer Function also sets the maximum Peak Luma Mapping, based on the selected Set White value.
Gamut selects the desired camera Gamut from a drop-down list defined by the camera manufacturer. Different camera formats have different options.
Using Camera Settings
Camera Settings can be used as 'Source' within Convert Colour Space, with the display's colour space selected as Destination, which will generated a Look LUT to take captured footage and display it in the correct colour space for the display being used.
Alternatively, using 'Destination' for the Camera Settings, with Source as a standard colour space, will generate a LUT to convert an image from the defined colour space back into the camera's colour space.
However, it should be understood that using default Camera Settings with standard colour space may not generate the expected LUT, as most camera transfer profiles include a linear portion near black. When generating a LUT direct to a 'calibration' colour space, the linear portion will generate an initial 'lift' from black. By default the LUTs generated will therefore be technically correct, but potentially not aesthetically pleasing.
To overcome this technically correct, but potentially non-desired result, LightSpace provides Tone Mapping using 'Viewing' based processing to negating the inbuilt camera transfer profile's linear portion near black. The initial 'None' setting applies no Viewing based processing or Tone Mapping, with the 'Viewing', 'Low', 'Medium', and 'High' options all using Viewing based processing, aimed at generating aesthetically pleasing Look LUTs.
In the above example, a Look LUT will be generated for Red camera footage shot Red Log3G10, clipping white at 100%, with Gamut set for RedWideGamutRGB, for display on a standard Rec709 monitor, based on RED's IPP2 colour processing, with no creative intent included - no Tone Mapping.
However, as can be seen above the generated LUT will have a Gamma profile that includes a lift near black, which while technically correct may not be ideal for a viewing LUT.
For a viewing LUT, selecting the 'Viewing' option within Tone Mapping will negate the lift near black, generating the following result.
This is a 'Viewing LUT' rather than a technical LUT, due to the use of the 'Viewing' option within Tone Mapping, a more 'appealing' LUT could be generated using one of the additional Tone Mapping options, potentially with a change in the Exposure setting, and even a different Peak Luminance Mapping setting.
The following shows the application of a 'Medium' Tone Mapping setting, with the Peak Luminance Mapping set back to its maximum value.
And you can directly compare the results here. Notice the subtle roll-off in both highlights and shadows via the use of Tone Mapping.
RED to Rec709 no Tone Mapping
RED to Rec709 with Medium Tone Mapping
And a comparison of the LUT's Gamma curves.
RED Rec709 LUT no Tone Mapping
RED Rec709 LUT with Medium Tone Mapping
Selecting the different Tone Mapping options, in combination with different values for Peak Luminance Mapping, Push/Pull Exposure, Set Black, Set White, etc., many different creative Look LUTs can be generated.
Using the technical LUT generation capabilities of the Camera Settings option enables the relative (direct) comparison of different cameras, comparing the different gamma curves, contrast range, gamut coverage and colour mapping each camera natively possesses.
And following the above, it should become obvious that using different Cameras for Source and Destination will generate a Conversion LUT to transform from one camera's colour space and transfer function to another. Such conversion LUTs can tell you a lot about the actual capabilities of the different cameras...
Note: When performing camera-to-camera matching the cameras needs to be 'User Saved' Camera profiles, not the initial in-built Camera pre-seta, as you cannot use two in-built camera profiles concurrently.
Remember, any Camera settings can be save as a 'User Saved' pre-set to enable quick access to regularly used settings, exactly the same as any 'Colour Space'.
Additional Technical & Support Info.
German language version of this page: displaycalibration.de